There are basically three types of hair color: temporary, semi-permanent, and permanent. Temporary hair color includes the so-called rinses that individuals use to color their hair for a one day event (e.g. red hair on Valentines day) and typically wash out with one shampoo. Semi-permanent hair color is used by individuals who desire to color their hair for a longer period of time. Typical semi-permanent hair color washes out after six to twenty four shampoos. Permanent, or oxidative, hair color provides permanent color that does not wash out with shampooing. Both temporary and semi-permanent hair color are direct application—that is the hair color is applied directly to the hair and will impart color immediately. The unused hair color can be saved and used again for other applications. Most individuals who color their hair use oxidative hair color in either a retail kit or salon environment. The oxidative hair color process involves mixing a separately stored oxidative dye composition with an aqueous based oxidizing agent, then immediately applying the mixture to the individual's hair for a period of time necessary to color the hair, usually from 5 to 80 minutes. The oxidative dye composition reacts with the aqueous based oxidizing agent to form colored dye molecules once they are absorbed into the hair shaft and impart color. The dye mixture thus obtained is very labile and must be applied to the hair very shortly after it is prepared. In fact, even an oxidative dye composition alone with time will even erode the effectiveness of the oxidative dye composition alone, even before it has been combined with the oxidizing agent. The extreme instability of oxidative dyes creates problems for hair salons where oxidative hair dye procedures are a major segment of their business. In a typical salon environment the oxidative dye composition is stored in containers such as tubes. The salon has many different colors of dye to facilitate mixing colors to provide the customer with the desired hair color. In most instances only a small fraction of the oxidative dye in the container is used in one procedure, and the remaining oxidative dye composition is stored for later use in other applications. However, due to the instability of the dye compositions under regular atmospheric conditions, they will sometimes be rendered ineffective, or worse yet, be used to dye hair, providing an unsuccessful result and an unhappy customer.
Hair dye manufacturers try to improve the stability of oxidative dye compositions by formulating them with various antioxidants. Ascorbic acid is one commonly used antioxidant. However, it very rapidly loses its activity when exposed to air so that once the dye containers are open the ascorbic acid is no longer an effective antioxidant. The result is that the dyes become rapidly oxidized by air and lose effectiveness. Another typically used antioxidant, sodium dithionate, is sometimes malodorous in addition its propensity for undergoing undesirable secondary reactions with nitro-based dyes. Erythorbic acid is also widely used but exhibits certain undesirable properties. There is a need for antioxidants for use in formulating hair dye compositions that maximize the stability of the oxidative dyes to facilitate multiple uses and interim storage of oxidative dye compositions until depleted. Additionally, it is desirable that such antioxidants be natural ingredients rather than synthetic organic compounds.
It has been discovered that certain antioxidants, specifically those containing at least one flavanoid component and/or at least one phenolic acid component provide excellent antioxidant properties when formulated with oxidative hair dye compositions, facilitating long term storage and multiple uses of the oxidative dye product once the container is opened.